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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Key cell structures at each surface Microvilli, Cilia, Stereocilia Specialized junctions Basement membrane - Sheet between the epithelial and connective tissue layers
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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Tissues Groups of cells similar in structure and function
Most organs contain all 4 types Tissue has non-living extracellular material between its
cells
The four types of tissues Epithelial Connective Muscle Nerve
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelial Tissue Cellularity – composed almost entirely of cells; little or no
extracellular matrix Polarity – apical and basal surfaces Special contacts – form continuous sheets held together by
tight junctions and desmosomes Supported by connective tissue – reticular and basal
laminae Avascular but innervated – contains no blood vessels but
supplied by nerve fibers Regenerative – rapidly replaces lost cells by cell division
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Key cell structures at each surface
Microvilli, Cilia,Stereocilia
Specialized junctions
Basement membrane - Sheet between the epithelial and connective tissue layers
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Classification of Epithelia
Figure 4.1a
Number of layers Shape
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelia: Glandular A gland is one or more cells that makes and secretes
an a particular product (secretion) Two groups – endocrine and exocrine
Endocrine glands are ductless glands that produce hormones and secrete into the blood stream
Exocrine glands Secrete their products onto body surfaces (skin) or into body cavities through ducts
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Exocrine Glands More numerous than endocrine glands Examples include mucous, sweat, oil, and salivary
glands Exocrine glands are classified according to number of
cells: The only important unicellular gland is the goblet
cell that produce mucin (glycoprotein) that when dissolved in water forms mucus.
Multicellular exocrine glands are composed of a duct and secretory unit
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Connective Tissue Functions Support – bone, cartilage, ligaments, tendons,
capsules encasing organs, organ stroma Medium for exchange of metabolic waste,
nutrients, oxygen – between blood and many cells.
Defense and protection – blood cells, physical barrier.
Storage of fat.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Structural Elements of Connective Tissue Have 3 main elements:
Ground substance – unstructured material that fills the space between cells
Fibers – collagen, elastic, or reticular Cells – fibroblasts, chondroblasts, osteoblasts, and
hematopoietic stem cells
Extra
cellu
lar
mat
rix
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Fibers Collagen –
Built primarily from the protein collagen Tough fibers Provides high tensile strength*
Elastic Long fibers Contain the protein elastin that allows stretch and recoil. Found in place that need elasticity: lungs, blood vessels
Reticular Short branch collagenous fibers that form delicate networks Support soft tissue of organs (ex. Around blood vessels)
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Cells Fibroblasts –
Can be found connective tissue proper. The most common resident cells in ordinary connective
tissue. Fibroblasts are responsible for secreting collagen
Chondroblasts – cartilage Osteoblasts – bone Hematopoietic stem cells – blood Immune system cells - White blood cells, plasma cells,
macrophages, and mast cells
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Areolar Connective Tissue: Model
Figure 4.8
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Types of connective tissue
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
membranes Membranes are a combination of more than one tissue They all are multicellular sheets composed of at least 2
primary tissue types: epithelium that is bound to an underlying connective tissue proper.
There are 3 types: cutaneous mucous serous
The synovial membrane is composed of connective tissue only
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelial Membranes:Cutaneous Membrane
Cutaneous – skin
Figure 4.12a
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelial Membranes: Mucous Membrane Mucous – lines body cavities
open to the exterior e.g., digestive and respiratory tracts)
Moist membranes Most ET are simple
columnar or stratified squamous
The underlying CT – lamina propria
Absorption and secretion
Figure 4.12b
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Epithelial Membranes: Serous Membranes
Figure 4.12c
Serous – moist membranes found in closed ventral body cavity Consists of squamous ET resting on loose CT Serous membrane is named according to the site and organ: lungs – pleura; heart – pericardium; abdomen - peritoneum
